There is a printer for issuing printed papers such as tickets for entertainment or receipts as acknowledgement of a money transfer. Such a printer includes a printing unit having a platen roller rotatably supported around its shaft, a power unit including a stepping motor and a gear train which drives the stepping motor to transfer a force generated by the stepping motor to the platen roller and rotate the platen roller around the shaft, a cutting unit provided at a further downstream of a forward direction than the platen roller to cut a paper at a certain position of the paper and a control unit to control the driving of the stepping motor and the operation of the cutting unit. The forward direction is a direction in which the paper printed by the printing unit is fed by the forward rotation of the platen roller.
Such a printer performs a desired printing on papers with the printing unit while feeding the paper in the forward direction by the forward rotation of the platen roller. After the printing of the printing unit, the control unit rotates the platen roller forward by driving the stepping motor by a first number of steps to feed the paper to the downstream of the forward direction and place a certain portion (unprinted portion at more upstream than the printed portion) of the paper at a predetermined position of the cutting unit.
Here, the platen roller is rotated by transferring the force generated by the stepping motor driven by the control unit to the platen roller via the gear train.
Furthermore, due to the backlash of the gear train as the power unit, the platen roller may rotate idly (rattle) in the paper feeding direction by the amount of backlash.
By the idle rotation of the platen roller, a printing position of the printing unit may be shifted and illegible lettering may occur due to overlapping printing caused by insufficient paper feeding.
In view of this, a printer which can remove the backlash by reversely rotating the stepping motor by the amount equal to or exceeding the backlash has been proposed (Patent Documents 1, 2).
In addition, a driving method of the stepping motor of the printer has been proposed, which removes the backlash by rotating the stepping motor by a predetermined number of steps in the forward direction corresponding to the paper feeding direction after power-on or paper cutting (Patent Documents 3, 4).